Liquid comestibles, commonly are offered to the consumer contained within closed (sealed) containers formed from laminates which include a paperboard substrate having at least one or more outer barrier layers. Such barrier layers insulate the paperboard from access to moisture originating either internally or externally of the container. At times, the barrier layer(s) further bar or reduce the transfer of gas through the container wall. The outer layer, at times, may comprise a heat sealing layer, which may also serve a barrier function.
Access to the contents of the container is commonly afforded by inserting a common drinking straw through an opening defined in the wall of the top end of the container. Such areas have heretofore taken many forms, such as multiple slits radiating from a central point and extending partially or fully through a wall of the container, partial perforations through the container wall, or other techniques. Most commonly, such areas are defined employing cuts partially through the thickness of the container wall, thereby permitting the rupture of the area using a common drinking straw, for example, to thereby gain access to the interior of the container. Also, the prior art includes the technique of providing slits or cuts through most or all of the thickness of the wall of the container, with these slits or cuts being temporarily sealed with a removable patch, cover, or a flap of the container.
It is noted that in the industry there exists containers for comestibles such as milk for example, wherein the container is of a lidded cup geometry. However, in certain of these containers, the opening for gaining access to the contents of the container is located at the bottom of the container, i.e., at that end of the container opposite the lid. In the present disclosure, the term “top wall” of the container is to be construed as referring to that wall of the container through which access to the contents of the container is achieved employing an opening as disclosed herein. Thus, in the aforedescribed lidded cup, the “top wall” of such container would include the actual bottom wall of the cup.
These prior art techniques for weakening the container wall for insertion of a drinking straw, for example, suffer from various problems. Obviously, unsealed full cuts through the thickness of the container wall are impermissible. Weakening an area of the container wall by cutting partially through the thickness of the wall requires precise cutting of the blank from which the container is ultimately formed. Known commercial production equipment used for this purpose has been found unreliable for producing such partial thickness cuts. Such unreliability is exacerbated by variances in the thickness of the laminate being cut as well as other factors.
Attempts have been made in the prior art to produce weakened areas in the container wall by embossing a pattern in the container wall. In certain containers formed from paperboard laminates and intended to contain a liquid, it is permissible that one or more, but less than all, of the layers of the laminate to be ruptured in the course of defining an opening to be used for future access to the contents of the container. This is true, for example, with containers for liquids having a short shelf life, such as milk. With containers for other liquids such as orange juice, it is impermissible that the liquid in the container be allowed access to the fibers of the paperboard substrate of the laminate. Known embossing patterns and their techniques of production have been found to rupture the outer layers of barrier or sealing materials that are laminated to one or both of the opposite surfaces of a paperboard substrate, thereby exposing the absorbent fibers of the paperboard to soak up liquid from inside the container, or to soak up liquid from the exterior of the container, either such event destroying the ability of the laminate to contain the contents of the container within the container, or permitting inadvertent puncture of the weakened area of the container wall. In more severe instances, leakage of the container contents results, while in any such instance, the purity, flavor, etc. of the container contents may be compromised. Whereas, as noted, rupture of one or more of the barrier or sealing layers of a paperboard laminate to be used to form containers for liquids, is permissible in certain containers, such layer rupture is not permissible in other containers for liquids. Known prior art techniques, including known embossment patterns, have been found to be lacking in their ability to consistently provide a weakened area in a wall of a container for liquids employing a paperboard laminate, wherein the weakened area remains intact to the extent necessary to retain the contents within the container and/or to protect the contents of the container against undesired alterations of the contents of the container, and still is readily rupturable by a common drinking straw.